Hi. We do recommend adding macroalgae to a newly setup marine tank earliest after the cycling has finished and the microalgae bloom is over, as the microalgae otherwise might in such an early stage to easily overgrow most newly added macroalgae.  As well you will need to have sufficient nitrate and phosphate for the macroalgae available, we recommend to have at least 2-3 ppm nitrate and 0.02-0.02 ppm phosphate.
When you are looking for macroalgae for critters have a look HERE please, it says macroalgae for herbivore fishes, but some critters will like them too, especially Ochtodes, Ulva, Codium and the red turf macroalgae species.
We have a lot of snails and crabs in our tanks, which actually mainly eat any microalgae, rather than the macroalgae, luckily :) Just be careful when you have Urchins or very large crabs or snails, as they might eat your whole new macroalgae very fast.
When you have any further questions please let us know.
Kind regards
Manfred - Livealgae UK