Once you have created your unhosted wallet on Paymium, please install the Electrum application from this link.
Electrum is a free software to restore your unhosted bitcoin wallet and access to your funds.
Please follow the steps on Electrum:
1- Click on File then on ‘New / Restore‘ and select ‘Standard wallet’, then click on ‘Next’,
2- Select ‘I already have a seed’, then click on ‘Next’,
3- Enter your 12 words delimited by spaces, then click on ‘Next’,
4- Select 'BIP39 Seed', then click on ‘OK’,
5- Check that the checksum is ‘OK’ and click on 'Next',
6- Select the legacy address type, choose the derivation path ‘m’ (delete the pre-existing path) and click on ‘Next’.
7- Select the legacy address type and click on ‘Next’.
That is it, your portfolio restoration is complete!