diff --git a/.env.example b/.env.example
index 12dd2928..2c4c0092 100644
--- a/.env.example
+++ b/.env.example
@@ -40,4 +40,4 @@ PERMANENT_API_BASE_PATH=${LOCAL_TEMPORARY_AUTH_TOKEN}
 # See https://fusionauth.io/docs/v1/tech/apis/api-keys
 FUSION_AUTH_HOST=${FUSION_AUTH_HOST}
 FUSION_AUTH_KEY=${FUSION_AUTH_KEY}
-FUSION_AUTH_APP_ID=${FUSION_AUTH_APP_ID}
+FUSION_AUTH_SFTP_APP_ID=${FUSION_AUTH_SFTP_APP_ID}
diff --git a/src/classes/AuthenticationSession.ts b/src/classes/AuthenticationSession.ts
index 666dae14..69210477 100644
--- a/src/classes/AuthenticationSession.ts
+++ b/src/classes/AuthenticationSession.ts
@@ -13,6 +13,8 @@ enum FusionAuthStatusCode {
 }
 
 export class AuthenticationSession {
+  private static readonly sftpFusionAuthAppId = process.env.FUSION_AUTH_SFTP_APP_ID ?? '';
+
   public authToken = '';
 
   public refreshToken = '';
@@ -23,8 +25,6 @@ export class AuthenticationSession {
 
   private readonly fusionAuthClient;
 
-  private readonly fusionAuthAppId = process.env.FUSION_AUTH_APP_ID ?? '';
-
   private twoFactorId = '';
 
   private twoFactorMethods: TwoFactorMethod[] = [];
@@ -78,13 +78,12 @@ export class AuthenticationSession {
 
   private processPasswordResponse([password]: string[]): void {
     this.fusionAuthClient.login({
-      applicationId: this.fusionAuthAppId,
+      applicationId: AuthenticationSession.sftpFusionAuthAppId,
       loginId: this.authContext.username,
       password,
     }).then((clientResponse) => {
       switch (clientResponse.statusCode) {
-        case FusionAuthStatusCode.Success:
-        case FusionAuthStatusCode.SuccessButUnregisteredInApp:
+        case FusionAuthStatusCode.Success: {
           if (clientResponse.response.token !== undefined) {
             logger.verbose('Successful password authentication attempt.', {
               username: this.authContext.username,
@@ -93,11 +92,22 @@ export class AuthenticationSession {
             this.authTokenExpiresAt = clientResponse.response.tokenExpirationInstant ?? 0;
             this.refreshToken = clientResponse.response.refreshToken ?? '';
             this.authContext.accept();
-            return;
+          } else {
+            this.authContext.reject();
           }
-          this.authContext.reject();
           return;
-        case FusionAuthStatusCode.SuccessNeedsTwoFactorAuth:
+        }
+        case FusionAuthStatusCode.SuccessButUnregisteredInApp: {
+          const userId: string = clientResponse.response.user?.id ?? '';
+          this.registerUserInApp(userId)
+            .then(() => { this.processPasswordResponse([password]); })
+            .catch((error) => {
+              logger.warn('Error during registration and authentication:', error);
+              this.authContext.reject();
+            });
+          return;
+        }
+        case FusionAuthStatusCode.SuccessNeedsTwoFactorAuth: {
           if (clientResponse.response.twoFactorId !== undefined) {
             logger.verbose('Successful password authentication attempt; MFA required.', {
               username: this.authContext.username,
@@ -105,16 +115,18 @@ export class AuthenticationSession {
             this.twoFactorId = clientResponse.response.twoFactorId;
             this.twoFactorMethods = clientResponse.response.methods ?? [];
             this.promptForTwoFactorMethod();
-            return;
+          } else {
+            this.authContext.reject();
           }
-          this.authContext.reject();
           return;
-        default:
+        }
+        default: {
           logger.verbose('Failed password authentication attempt.', {
             username: this.authContext.username,
             response: clientResponse.response,
           });
           this.authContext.reject();
+        }
       }
     }).catch((clientResponse: unknown) => {
       const message = isPartialClientResponse(clientResponse)
@@ -125,6 +137,29 @@ export class AuthenticationSession {
     });
   }
 
+  private async registerUserInApp(userId: string): Promise<void> {
+    return this.fusionAuthClient.register(userId, {
+      registration: {
+        applicationId: AuthenticationSession.sftpFusionAuthAppId,
+      },
+    }).then((clientResponse) => {
+      switch (clientResponse.statusCode) {
+        case FusionAuthStatusCode.Success:
+          logger.verbose('User registered successfully after authentication.', {
+            userId,
+          });
+          break;
+        default:
+          logger.verbose('User registration after authentication failed.', {
+            userId,
+            response: clientResponse.response,
+          });
+      }
+    }).catch((error) => {
+      logger.warn('Error during user registration after authentication:', error);
+    });
+  }
+
   private promptForTwoFactorMethod(): void {
     const promptOptions = this.twoFactorMethods.map(
       (method, index) => `[${index + 1}] ${method.method ?? ''}`,