Sounds very strange. It is not correct usage so it's hard to guess what they mean with achieve! Sorry

Weird EN - sounds like a babelfish translation from German --> EN

Achieve??? -> reach? new tenants (through advertising, word of mouth, etc...)???

My English suggestion (maybe will help with German):
Our commercial leasING department has received permission to advertise for new tenants. (I think new would cover "incoming")
This service will be paid for by the tenants???? (account for = verrechnen??)

If at all possible, try to speak to whoever wants this translated. Good luck!!

Thanks for confirming that this is weird English and thanks for the try. I will ask the author on Monday.

Nice weekend!