Flask in EC2 [wsgi:error] ImportError: No module named

I follow this tutorial https://www.codementor.io/@jqn/deploy-a-flask-app-on-aws-ec2-13hp1ilqy2 to setup Flask in EC2. Everything works well up to Step 3 (where index.html from flask folder is served). But as soon as I move to Step 4 (to enable Flask Python app, and link it to Apache), I got the below error.

Any suggestions? Thank you in advance

[Thu Jan 07 01:36:14.607338 2021] [wsgi:error] [pid 1387:tid 140388356159232] [client 119.74.148.227:30755] mod_wsgi (pid=1387): Exception occurred processing WSGI script '/var/www/html/flaskapp/flaskapp.wsgi'.  [Thu Jan 07 01:36:14.607434 2021] [wsgi:error] [pid 1387:tid 140388356159232] [client 119.74.148.227:30755] Traceback (most recent call last):  [Thu Jan 07 01:36:14.607522 2021] [wsgi:error] [pid 1387:tid 140388356159232] [client 119.74.148.227:30755]   File "/var/www/html/flaskapp/flaskapp.wsgi", line 5, in <module>  [Thu Jan 07 01:36:14.607622 2021] [wsgi:error] [pid 1387:tid 140388356159232] [client 119.74.148.227:30755]     from flaskapp import app as application  [Thu Jan 07 01:36:14.607708 2021] [wsgi:error] [pid 1387:tid 140388356159232] [client 119.74.148.227:30755] ImportError: No module named flaskapp  

https://stackoverflow.com/questions/65605738/flask-in-ec2-wsgierror-importerror-no-module-named January 07, 2021 at 10:08AM