Management Portal: Purchase Licenses and Services option is disabled on Management portal
If you find that you can't find The "Purchase License and Services" icon on management portal, this may be due to limitations to your current user under the Management Portal account of your organization.
You may need to consult with your main administrator of your Management Portal Account, so that he or she can grant you adequate permissions to access our store and perform purchases.
As the linked document suggests, roles are very manageable and different profiles can be set to accommodate to your organization's needs.
Your account will have to be assigned to a proper role profile that contains the Purchase Licenses feature checked.