Rather than inserting the private key into Electrum upon first start, you should set it up another way.
Have you followed every single step properly from the link above (
https://support.ledger.com/hc/en-us/articles/115005161925-Set-up-and-use-Electrum)? It's not a link to a download, it's a tutorial!
When you open Electrum, go to File and create a new wallet by following the link above. But the thing is, if Ledger Live doesn't see BTC balances, you most likely will not see any balance on Electrum either.
When you plug your Ledger into your PC and unlock it using the PIN code you set up, do you have the Bitcoin app on your Ledger display? If yes, enter it. You should see the "Application ready" message on your Ledger. Then, open up Ledger Live and add new accounts for Bitcoin. Give it some time for it to scan multiple accounts - are all the accounts that show up fully empty?
After adding the accounts for BTC, in the Ledger Live dashboard (where you see the graph of your money, right under it) you should have a history of transactions... do you see any transaction there? If yes, then you have the right seed but you have previously spent all your BTC..
The seed should never be introduced on a PC. It should sit on an offline thing (such as a paper). When you insert it manually in a computer, it removes the purpose of a Ledger which is to store your seed and private keys in an offline device!