This is from the webpage you referenced...
- Each one needs 15-20mA Driver Current
20mA * 8 = 160mA. The absolute maximum for the processor is 200mA. With some good luck and careful planning you may be able to drive 13 relays. There are various other limits that will likely restrict the number of relays to something less than 13.
The goal is 32 relays. 32 * 15mA = 480mA. There is a very high probability that 480 mA will severely damge your board.
I may need to get an 8 channel relay board with Optical Isolation
That is not necessary. But, given your goals, a transistor between the board and the relay is necessary.
Were I in your shoes, I would look for a better relay board.