Having trouble purchasing a domain name - any advice?

Hi

I’m a beginner here, I’ve been trying to purchase a domain name, but i keep having an error message saying: “Address must not have contain character etc. etc…” even though there is no special character in the address.

also i signed for the free trial and purchased the Basic plan but afterward each time having trouble to sign back in again …so right now i have like 3 different Accnt that i will get charged after free trial end and i can’t get access to the site …

I will really really appreciate some assistance please…

thank your

Denis