bike fit calculator on competitivecyclist.com, accessing from .de
Looks like you're in Europe, and that website has chosen to reject your traffic because of that.  I've just tested from an AWS host in Frankfurt and seen the same result.
The text is

You're probably wondering why you've landed here of all places. Well, as of 25.05.2018, CompetitiveCyclist is no longer available outside the US due to GDPR regulations...&quot;

then directs you to that .de site.
Essentially your collective nations'  GDPR requirements have been rejected, a case of &quot;nah don't want to play with you&quot; from competitivecyclist.com.   Upshot, you risk breaching your own nation's laws about GDPR by dodging them.
No matter how you cut it, this is a legal question about EU laws, and a technical question about web-based filtering.
This question has only minor tangential relation to bicycles or cycling, and the same fundamental question would remain if your destination website was http://llamapajama.com/   As such, this fails the &quot;on-topic&quot; test and will be closed.  Please don't take it personally.  You may choose to ask this on law.stackexchange.com - it is not really detailed enough to migrate as-is.