Reference:
https://docs.microsoft.com/en-us/powershell/module/teams/new-team?view=teams-ps
https://docs.microsoft.com/en-us/powershell/module/teams/add-teamuser?view=teams-ps

To configure a virtual receptionist for your company's main office, you can use the Teams admin center to create and assign an auto attendant. An auto attendant is a voice menu system that allows callers to be transferred to an extension or a queue without speaking to an operator or receptionist. Here are the steps to create and assign an auto attendant that meets your requirements:
* Sign in to the Teams admin center with your Microsoft 365 username and password.
* In the left navigation, go to Voice > Auto attendants.
* Click Add (+) to create a new auto attendant.
* In the Basics tab, enter a name and an optional description for the auto attendant, such as "Main Office Receptionist".
* Under Phone number, select Assign and then choose a service number from the list or click Add new number to get a new one. A service number is a type of phone number that can handle hundreds of simultaneous calls and is used for services such as audio conferencing, auto attendants, and call queues.
* Click Apply and then Next.
* In the Greeting and menu tab, under Greeting, select Custom and then click Upload audio file to upload a recorded greeting message for the callers, such as "Welcome to Microsoft. Please listen carefully to the following options."
* Under Menu options, click Add (+) and then select Key press from the drop-down menu.
* In the Key press box, enter 1 and then select Dial by name from the Action drop-down menu. This will allow callers to press 1 for the company directory to lookup by name.
* Click Add (+) again and then select Key press from the drop-down menu.
* In the Key press box, enter 0 and then select Play audio file from the Action drop-down menu. This will allow callers to press 0 to hear the company address.
* Click Upload audio file and then upload a recorded message with the company address, such as "Our main office is located at 1 Microsoft Way, Redmond."
* Under Menu options, turn on the toggle for Repeat menu until caller hangs up or presses #. This will offer the same menu at all times.
* Click Next.
* In the Business hours tab, under Business hours, select 24/7 from the drop-down menu. This will make the auto attendant available at all times.
* Click Next.
* In the Review tab, review your settings and then click Save.
Now, you have configured a virtual receptionist for your company's main office that meets your requirements.

Reference:
https://docs.microsoft.com/en-us/microsoftteams/teams-live-events/set-up-for-teams-live-events

To ensure that the Approvals app is pinned to the top of the app bar of the Teams client for all members of the Retail team, you need to create a custom app setup policy and assign it to the Retail team members. Here are the steps to follow:
* Sign in to the Teams admin center with your admin credentials.
* Go to Teams apps > Setup policies.
* Select Add.
* Provide a name and description for the policy, such as Retail App Policy.
* Optionally, turn on User pinning to allow users to pin apps and change the order of the pinned apps.
* Under Pinned apps, select Add apps.
* Search for the Approvals app and add it to the list of pinned apps. You can also add other apps that you want to pin for the Retail team members.
* Click Save to create the policy.
* To assign the policy to the Retail team members, go to Users on the left menu and select the users that belong to the Retail team. You can use the filters or the search box to find them.
* On the right pane, under Policies, select Edit next to App setup policy.
* Choose the Retail App Policy from the drop-down list and click Apply.