I've been down your road before.
Upload your texture pack to dropbox.com. Copy link, set "dl=0" to "dl=1" and paste it in the Resourcepack Settings click 'Save' and restart your server. If it doesn't work, it's a problem with your texture pack. Make sure the 'items' folder in your texture pack is named 'item' and 'blocks' folder is named 'block'.
If it doesn't prompt you, make sure you have Resourcepack Prompt enabled from the main menu of the multiplayer server list. If it's enabled, it's a Minehut issue that it's not loading. Specifically, it won't prompt if you already have it on.
Try joining from direct connect, then it will likely load.