To expand on this with setting up email access policy and access login code using Cloudflare Zero Trust:
Go to setting>General>"Access Policy(Enabled)"Managed
Setup your Zero Trust Plan if not already done (You can use Zero Trust Free. Its Free )
Next, add and configure your application:
Under Policies, you can edit the existing default policy:
To keep it simple you can just use Emails for testing.
Go back to Policies and Test:
So if you use email access policy type, you should have a page like this below for access:
Play around with other authentication types that fits your needs.
Read more about CloudFlare Zero Trust Add web applications · Cloudflare Zero Trust docs
and @aliasfox thanks for the guide!! worked for me, did not have any issues.