Option 1

You may use Tableau Viz Extensions starting from the release version 2024.2 which uses the API capability for you to create custom extensions to access all sorts of new Viz Types.

Tableau | Radar - Radar

Tableau | Radar Chart - Radar Chart

Option 2
In Tableau Desktop, add a background image  to the view, and then add X and Y coordinates to the data source to plot data over the background image. For more information, see Radar Charts in Tableau – part 1 in the Information Lab blog.

Option 3
The attached workbook RadarChart.twbx is created from the attached excel file SampleData.xlsx to demonstrate the following steps.

1. Open SampleData.xlsx and add rows that KPI Name is KPI8 for each member. The KPI Value of KPI8 should be the same as that of KPI1 for each member.
   In the Edited_SampleData sheet of SampleData.xlsx, the rows added in this step are colored by green.
2. Add rows that Member is MAX for the same number of members included in the data source. The KPI Value of  MAX should be the maximum value of the rader chart.
   In the Edited_SampleData sheet of SampleData.xlsx, the rows added in this step are colored by yellow.
3. Open the edited data source by Tableau Desktop.
4. Click Analysis > Create Calculated Field, name the new calculated field as 1.INDEX with the following formula.

   INDEX()
   

5. Create a calculated a new field named as 2.KPI Counts with the following formula.

   {FIXED:COUNTD([KPI Name])}-1

6. Create a calculated a new field named as 3.Radians with the following formula.

   PI()/2 - 2*PI()/avg([2.KPI Counts])*([1.INDEX]-1)

7. Create a calculated a new field named as 4.X Coordinate with the following formula.

   SUM([KPI Value])*COS([3.Radians])

8. Create a calculated a new field named as 5.Y Coordinate with the following formula.

   SUM([KPI Value])*SIN([3.Radians])

9. Create a calculated a new field named as 6.Labels with the following formula.

   IF [KPI Name]="KPI8" THEN NULL ELSE [KPI Value] END

10. On the marks card, select Line and place Member to color, KPI Name to path, 2.KPI Counts to details and KPI Values to labels.
11. Place 4.X Coordinate to columns and 5.Y Coordinate to rows.
12. Right-click 4.X Coordinate in columns > Edit Table Calculation.
13. Select Specific Dimensions and arrange dimensions in the order of Member,  KPI Names from the top, then check both dimensions. Select Member for the Restarting every setting.
14. Right-click 5.Y Coordinate in rows > Edit Table Calculation.
15. Select Specific Dimensions and arrange dimensions in the order of Member,  KPI Names from the top, then check both dimensions.
16. (Option) Add Members to filters.