I have only one server which already has SQL server installed.

Have domain accounts that have full control of the server machine but only read permission of Active Directory.

Can I install Sharepoint and workflow manager on the same server? 

If I do a stand alone installation can I use local accounts to finish everything?

Yesterday I used my domain account to install Sharepoint(Stand alone) and my local account to install workflow manager(My domain account does not work, it gives me error saying(Invalid RunAs account). I connected workflow manager and sharepoint but when I try to open the site I got this:

<Code>AuthorizationError</Code>
<Message>
The caller does not have the necessary permissions required for this operation. Permissions granted: None. Required permissions: ReadScope.
</Message>

I am totally new to Sharepoint and don't know where the problem is.

You can do a stand alone installation (SQL, SharePoint, WFM on a single server), but you must use domain accounts for the services. One thing you'll want to do is provision the UPSS or AD Import, since you'll need User Profile