Once the pack is in your resourcepacks folder, you still need to switch it on and check that the new textures are loading.
Enable the pack
1. From the title screen or the pause menu, open Options, then Resource Packs.
2. Find Gothiclily's Flower Pack in the Available list on the left.
3. Click the arrow on its icon to move it to the Selected list on the right.
4.
If the pack is not in the list, click Open Pack Folder and check that the file is directly inside resourcepacks, not inside an extra subfolder.
Quick test in a world
The crafting table is the easiest block to check.
- Crafting table: Place one or look at it in your inventory. The pack swaps the standard texture for a new design. If it looks like the vanilla table, the pack is not active or another pack is overriding it.
- Common flowers: Place a
poppy, a 
dandelion and an 
oxeye daisy. All three get new details. - Nature blocks: Look at nearby
grass and ferns. These are repainted too. - Tall plants: If you have a rose bush, peony, lilac or sunflower, place it and compare it to the vanilla look.
If some blocks look new and others do not, another active pack is probably covering them. Open Resource Packs again and move the flower pack higher in the Selected list.