Steps below if the PC has been joined to Domain

** It is recommended that you use your account first because it will gives the first account admin rights

1) Disjoin the PC from the Domain then reboot the PC

2) Settings > Accounts > Access work or school > Connect button > Join this device Microsoft Entra ID 

3) Sign with your Salvation Army email address and Microsoft365 password > MFA

4)  Choose Join > Done > Reboot the PC

Please watch video below.

https://www.youtube.com/watch?time_continue=216&v=gR8tu4iwnMw&embeds_referring_euri=https%3A%2F%2Fwww.google.com%2Fsearch%3Fq%3Dhow%2Bto%2Bentra%2Bjoin%2Ba%2Bdevice%2Bwindows%2B11%26sca_esv%3D0693a25b4e112fe7%26source%3Dhp%26ei%3DBWLFaduOC9GRm9cP94yB&source_ve_path=Mjg2NjY

Start at 2:04 to 4:03