Please confirm the following:
1. Make sure the email, username, and password are valid and fit the criteria (special characters can cause issues)
2. Try registering via the Desktop Site, instead of the Mobile Site. If on a phone and using the Chrome App, this can be done by clicking the three dots for the menu, and checking "Desktop Site"
(This shouldn't be the culprit, but why not test it quick)
3. Google "What is my IP address" - and enter that #.#.#.# into the lookup, here
https://www.dnsbl.info/ and here
https://www.projecthoneypot.org/search_ip.php
If your account is found on those lists, your IP address may have been used by spammers in the past.
4. Make sure the following email services aren't being used to register:
yopmail.com ; mailinator.com ; guerrillamail.com ; freemailnow.net ; fastmailnow.com
Other common spammy email domains are blocked, but those are probably the most common.