No you should be able to see them with or without an account with zoto.

FirstI would check your browser settings to make sure you haven't accidentally blocked images from zoto.com

Secondly, check your firewall settings and make sure zoto.com is on an allowed list.

If all else fails, check with your ISP to make sure they have not blocked the domain for whatever reason.

And finally, if all else fails, check your modem. It could be going dead. Though I don't think this is the problem, but it is a very faint possibility. Are you having problems accessing any other sites you have been able to access without a problem in the past?