Atlassian only do telephone support for the top-most level of support contracts.
For Cloud, you'll need to raise it at https://support.atlassian.com
However, there are a couple of layers to this we, as end users, can talk you through too.
Your Atlassian account is the one you use to buy the software. Hopefully, whoever did this will have named you as either a billing or technical contact, possibly both. If you don't have that access, then you definitely need to go to support for help, to get you added.
Your Confluence Cloud account is separate (although it may well be the same credentials). That lets you get into it as a user - are you and admin there?
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