You need to allow session cookies on an iPad. To allow session cookies on an iPad, you mainly need to adjust Safari privacy settings (and sometimes app-specific settings). Follow these steps carefully:

Allow Session Cookies in Safari (iPad)

Open Settings on your iPad.

Scroll down and tap Safari.

Under Privacy & Security, check the following:

• Block All Cookies → Turn OFF This is required.
  If it’s on, session cookies will not work.
• Prevent Cross-Site Tracking → Turn OFF (recommended for some web apps)
  Some applications rely on cross-site session cookies.

Scroll down and tap Advanced.

Ensure JavaScript is ON.

Clear Old Cookies (If Session Still Fails)

Sometimes stale cookies interfere with new sessions.

Go to Settings → Safari

Tap Clear History and Website Data

Restart Safari and try again