Maybe a bit late, but in case someone is havening a similar problem:

I realized if you know your product number you can use e.g. this link

https://data-bluebrixx.oss-eu-central-1.aliyuncs.com/manuals/104/104182_Manual first Version.pdf

and substitute the 104 for the first 3 digits of the product number, and then change the number after the slash to the rest of your product number.

That way you should be able to get every manual without an account.

Apart from that, a lot of blue brixx resellers offer the manuals on their own homepage mostly without an account.

Someone with a rabbit, but without a knife.