Hi! Thanks for your question. ERA can do what you need, just follow these steps:
1) Start the server, and click the "About" button on the lower right of the module selection screen.
2) Find the last line "To customize your rule set, click here." and... click there!
3) Open the options for the second box (Calculate Development Points) and choose "Fixed at 100".
4) Click the "Apply these values" button to close the dialog.
5) The next time characters level up, they will have 100 DP available to spend.
Let me know if you need anything else