do i need a sim card for my ipad?

No SIM or eSIM is required for Wi-Fi. Many iPads entirely lack cellular; are Wi-Fi-only models.

Here is what to do: If your iPhone or iPad won't connect to a Wi-Fi network - Apple Support

Return for a refund, if the troubleshooting does not resolve this.

And as problematic purchases arise all too often: The All Too Common SAD Reality of Buying … - Apple Community

If you have acquired a WiFi+Cellular model iPad, it is not necessary to add a DataSIM unless you intend to use Cellular connectivity in addition to WiFi. All models of iPad (i.e., WiFi+Cellular and WiFi Only) are equally capable of accessing WiFi networks without any reliance upon Cellular connectivity.

Assuming that you have either already successfully completed setup of the iPad - or are in the process of setting-up from the initial “hello” page and cannot connect to your WiFi network, start with basic WiFi troubleshooting:

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

Recommended settings for Wi-Fi routers and access points - Apple Support

Consider that your Router, to which you are attempting to connect, may be configured to require support for security features that may not supported by your iPad. If you have an older iPad and your router is configured for WPA3 or WPA3/WPA2 mixed authentication, you will need to change this to WPA2 PSK(AES). Only newer models of iPad support WPA3. During initial setup, ensure that you WiFi Router is not using MAC-based access control that expects specific MAC-addresses to be configured.

Be aware that some Mesh WiFi Routers are known to be troublesome in some circumstances.

If your WiFi has been set-up according to Apple’s recommended settings, WiFi and Internet connection difficulties are usually an indication that your device does not have a routable IP Address - your IP Address usually being assigned by DHCP. When this occurs, your iPad may only have a self-assigned link-local IP address that begins 169.254.x.x.

You can verify your DHCP-assigned IP Address from settings:

Settings > WiFi > [Your WiFi Network / SSID] - tap the blue “i” icon - [IPv4 Address] IP Address

If the iPad has been successfully setup - and you are able to access your iPad’s WiFi settings - check to see if your iPad is using the new WiFi Private Address feature. This feature is intended to provide additional privacy and security when using “public” (untrusted) WiFi networks.

Settings > WiFi > [Your WiFi Network / SSID] - tap the “i” icon - Private Address

The Private Address feature is largely unnecessary for your home WiFi network; if enabled, Private Addressing can cause issues if specific MAC addresses are expected by your WiFi Router. You may need to disable this feature - and can be enabled or disabled for each individual network.

Use private Wi-Fi addresses in iOS 14, iPadOS 14, and watchOS 7 - Apple Support

Check that you've gotten the WiFi password right, and haven't, say, entered the letter "O" where you need to enter the digit "0" (or something like that).

You would only need a nano-SIM card if

• Your iPad Mini 4 had the optional cellular data modem, and
• You wanted to be able to connect to the Internet using cellular data (e.g., to get directions while driving)