Moving shares you already hold at another broker across to your UOB Kay Hian account is done in the Bursa Anywhere app, not in a trading platform.
It is a transfer between CDS accounts. Nothing is bought or sold, and the shares stay yours throughout.
Search for Bursa Anywhere in the App Store or Google Play and install it. The listing is published by Bursa Malaysia, as shown here.
The app is used to check balances in Authorised Nominee CDS accounts and to transfer securities into Authorised Nominee accounts.
Open the app and complete the registration to create your Bursa Anywhere account.
You will need your identity documents and your CDS account number to hand.
My Services sits in the bottom navigation bar of the app.
Select the CDS account from which you wish to transfer your securities, then tap Next.
Check this is the account that currently holds the shares, not the one you are moving them to.
Select the counters to be transferred into your UOB Kay Hian account.
Transfers are not instant. Allow several working days, and do not plan to sell those shares in the meantime.