created a new account in the country of Montenegro.

[Edwrd1]

When other people try to send me money, an error appears that transfers are not available in the country

[kernowlass]

@Edwrd1 

The option to receive Paypal payments is sadly not available in Montenegro.
You can only send payments for purchases funded by your (confirmed) credit card.

Paypal varies a lot country to country and can only offer the services that the banks / governments of that country allow it to offer.
There are quite a few countries unable to receive Paypal payments.