Select the currency
For example, if you would like to exchange Bitcoin to Ethereum, type in the amount of BTC you would like to exchange in the “You send” section and choose “BTC” from the drop-down menu. Then choose “ETH” from the drop-down menu in the “You Get” section and the service will automatically calculate the amount of Ethereum you’ll get. If everything is OK, click on the “Exchange” button.
Enter your wallet address
Type in your Ether wallet address in the "Your ETH Address (destination address)" box. Click "Next". If you don’t have an Ethereum address, you can go to the "Don’t have a wallet yet?" section and create a wallet with one of our partner services.
Confirm
Check all the information carefully and click "Confirm".
Deposit
ChangeNOW will generate a Bitcoin deposit address for you. Send your BTC to that address.
Receive your coins
@OP also to avoid things like this happening since you are a newbie and the crypto industry is a whole new world for guys like you, I think for you not to get lost next time you must read some guides which you can find in the exchange itself on how buying ERC-20 tokens from them. Reading their guide it will clearly show you that you need to have a Ethereum address and not a Bitcoin address as your destination for your purchased cryptocurrency, I think what you did is you just copy and pasted your Electrum address as your receiving address without you knowing first the difference between a Bitcoin wallet address and a Ethereum wallet address.