I think if the blog has a good business model it should have a website and pays for domain and host, if it has a unique domain and some users here use it and make money then you can advertise for it.
that blog is not a useful to make money for free as the OP saying that mostly offers required a credit card and not available for all countries, OP just want to get some referral from this kind of trick so stay away from this you will not get paid from this service.
You will certainly receive your reward, gptcoin group only wish to use this method to stabilize the price of gptcoin.
We have our website under construction you can read that from the blog.