Funny, I had the exact same experience last night. I got a bamboo island and came back with an inventory full of Atlas moths, Jewel Beetles and Tarantulas and made over $150K with Flick. Isabelle was real cryptic until I put out enough stuff like swings and a lighthouse and Godzilla, a bunch of yard art type stuff. That's when my Island bumped up to a 2 star rating and she started getting a lot more specific. She told me to plant flowers, plant saplings, clean up weeds. So I did all that, planting about 20 flowers and 5 saplings, and picking up 100 weeds, and my island bumped up to 3 stars. The next morning, KK was there and I got the credits. Now I have an app that I can make paths and change landscapes. The upgrades cost 6000 bells to do rivers or cliffs, then the path options cost 2000 bells each. I now have every bug that I know of that is available to this point except for a snail. Waiting for rain for that one, apparently. I still need a Barreleye and a Golden Trout for known fish. I've wasted well over 400 baits going after that damned trout. I have two pools on top and I've fished both of them as well as their 2nd level rivers and nothing except a ton of Cherry Salmon, Dace, and Char. I've abandoned the Barreleye until I get the Trout.