In what way(s) did the password you tried to use not meet the password policy requirements?

Depends on the organization. Password policies differ between each organization. Generally on a mainstream point of view. Passwords should generally be complex. If your passcode is too short. This could pose a risk to your account and the companies data could be at risk.

Broad range of possible pass code rules that may be blocked.

7 character limit
Capital letter and/or number figure
No easy consecutive digit or character: e.g abcd1234

No, the only way you can mute the notifications is to disable notification sounds in the settings, the settings of your phone of