Gmail account problem

I have opened a gmail account on Multilogin (the software) using an IPv6 address.
After an hour I receive this message:
"We've detected unusual activity on the account you're trying to access. To continue, please follow the instructions below."
And they want me to verify its me with a phone number.

Why did this happen? and how do I avoid it next time?
Still all on Multilogin (the software)


Thanks

Are you using shared hosting. Make sure you have a dedicated IP assigned to your website with no previous blacklists and completely clean record. ask your host for it.