Do you have Brave installed as default browser?
If yes, this causes the issue
The Spencer app needs a browser in order to login, and it uses the browser that the OS, in this case, Android, decides that needs to be used.
Brave blocks all "external opens" and the login flow just stops
Chrome was installed but not default and the OS did not expose this to Spencer. Meaning: Spencer tried to open Chrome but the OS blocked it and did not provide Brave as an alternative browser to use.