You can bid on all the players you like, if you have what each player cost.

If you then win the auction, you go into debt.

I have had more debt at one point. I had about 400M, but bid on 12-14 new regens at the start of a new season.. Most of the players didn't came immediately, but was signed, so i had to get rid of my other players first.

I would guess thats the same in this case.