When we enter the web page we are presented with a form.
By looking at the source code we can see includes to two javscript files:
<script src="/static/js/2.f33b908f.chunk.js"></script> - auto generated script with all libraries
<script src="/static/js/main.c809b4b6.chunk.js"></script> - script that contains app login
By looking at the second script we can see some deobfuscated strings:

There are 2 functions of intrest here, D and I.
We can take those two functions and add insert them into the web development console.

Then we can call the function I with the first string and we get the flag: