If you'd like to send gifts by spending the funds in the Workspace Balance, you have 3 options:
A Workspace Admin can manually transfer funds from Workspace Balance to each Workspace Member's Balance.
A Workspace Admin can give the Workspace Member(s) access to spend Workspace Funds.
Even if you are the Workspace Admin, you are simply using your Workspace Member account when sending gifts, like any other Workspace Member. Meaning you'll need to follow one of the steps above.