Here are few items to check when embedding report chart to object page:
- the report is in a folder that’s shared with users who need access, not in private folder.
- the source report format is summary or matrix.
- the source report has a chart.
You can follow this document to add report chart to a page layout Add a Report Chart to a Page Layout.
Usually, when you embed report charts to page layout, you want to show the relevant data to the current record, such as Total Opportunity Amount by Stage for current Account, for this case, you can use Opportunity standard report type, as Account Id is available in Opportunity report type.
Note: for this scenario, Account Id or Account Name does not need to be present in the report.
When editing the page layout to add report chart, you can select the chart size, appearance, data refresh, and the data filter. Check out this document Filtering Report Charts to Show Data Relevant to the Page.
However, you can add only up to two report charts on a page. The good news, embedded Report Chart in page layout will work in both Classic and Lightning, even you can't see the Refresh button in Lightning, so the best option is to enable "Refresh each time a user opens the page" in the chart properties.