In the upgrade documentation at https://doc.owncloud.com/server/admin_manual/maintenance/upgrade.html#introduction you will read, that you first have to upgrade your current version to the highest available and then to the next major release. Once you have reached version 8.2.11 you can migrate the setup to the new server and have it upgraded to 10.1.1
In your case the upgrade path would be
7.0.x -> 7.0.15 -> 8.0.16 -> 8.1.12 -> 8.2.11 -> migrate -> 10.1.1
Older ownCloud versions are found at https://owncloud.org/download/older-versions/