Hi OlRed07, welcome to TPT! I did a quick search on Activeflora regarding your question and didn't come up with much either. I have never used this product so I can't speak from experience as to how it may affect inverts but, I can give you some insight regarding copper:
Just because copper(Cu) is present does not mean it is in high enough levels to harm inverts. This being said inverts are adversely affected by Cu at lower levels than vertebrates are affected. However, there are different thresholds at which individual species are affected and to different extents. I'm about to overgeneralize this next part so bare with me.. basically at non-lethal levels inverts may not be killed by Cu, but it may prevent them from breeding. Do some research to find out what those levels are to the species you want.
Cu is more toxic at lower pH. At higher pH values Cu is chemically bound to Carbonates. This doesn't remove the Cu but basically keeps it busy. So, depending on the kh and pH of your tank you may want to rethink using this substrate.
Choose a water conditioner that binds("detoxifies") toxic metals. And do regular water changes for a while.. two-three a week. You can buy Cu water test kits. Also, filter media like carbon, peat and, poly-fiber remove(bind) Cu at a molecular level. This may be something for you to take into consideration.
Plants clean water in more ways than using ammonia, nitrite and nitrate. They also detoxify heavy metals. Cu is toxic to plants in high enough levels however, plants NEED Cu in very, very small levels(in the parts per billion range as opposed to parts per million). A healthy and heavily planted tank will use some of this. Do a search for aquatic plants and metal toxicity and I think you will feel better.
In short I wouldn't worry about it too much. Get your tank up and running and your plants healthy. Before adding inverts get a Cu test and see what it says. If nothing registers then get some test inverts. Ghost shrimp and pond snails.
Hope this has helped or at least given you some insight.
Stock lightly and carry a big filter. - I don't have aquariums. I have ecosystems in a glass box. - Hygrophilaholic and hoarder of Anubias.