How dividend income should be shown?

Dividend income has to be shown "quarter wise " as per Inc tax definition of quarters ( five quarter in a previous year.)
Use Excel . Yes it's tedious but there's no way out. For dividend , there is some sec which has to be used for classification .That sec is there in the utility where dividend is to be filled .Just read it.As far as I remember it's not stating mutual fund and share segregation.The segregation between MF and share is for LTCG STCG income not for dividend income.
What is spectrum?

You can choose to report in 1st quarter for practical purposes where the dividend income is small and/or the interest component is not huge or there is no final tax liability

If quarter wise is not shown it may result in validation errors!

Simply take all your dividend credit entries that came in the bank account(s) by date, starting from 1st April 2020 upto 31st March 2021. Then group them in respective quarters. Adjust those entries in the excel as per the quarter dates defined by the Income Tax department. The quarter breakup should total the actual total of Dividend reported on Schedule IOS.