How to sweep from armory wallet?

I recently tried to get started in Bitcoins, bought some online and received on an armory wallet. Little did i know i needed to download the full blockchain, that i have no space for.

I tried to sweep using armory private keys (wallet/backup this wallet/export key list) into electrum and several other wallet but the wallets can’t seem to recognise the keys since the “sweep” button always stay grey.

I also tried to send the bitcoins to another address using omniwallet but armory can’t recognise and sign the transaction file.

What can i do ? I feel like i’m out of options