I have connected my site to Aruba through their nameservers, simply adding the A records. Now, i haven’t the nameserver management panel available, than I cannot insert Cloudfare’s namservers in my dns panel. Is there another procedure in this case to insert my site on Cloudflare?
Nope. Ask them to change the nameservers to those provided by Cloudflare or change your registrar if they don’t want to do it. According to the forums it is possible to change them