We're thrilled that you've chosen QuickBooks as your trusted partner in managing your clients' businesses, @will97. To effectively handle 100 clients or more, we recommend using QuickBooks Online Accountant (QBOA). I'd love to discuss this option further to ensure it meets your needs.

This plan is specially created to help accountants easily manage and add clients from one place. With QBOA, you can add as many as 2000 clients to a single account, making it a flexible option that can expand as your business grows. It includes a wide range of tools and features designed to simplify your accounting work and boost your productivity.

To get started with one, please follow these steps:

1. Please visit this website: https://quickbooks.intuit.com/global/accountants-software/.
2. Beside the Login button, select your country and choose your preferred language.
3. Once done, click the Free sign up for accountants.
4. You'll be routed to a new web page. If you're new to QuickBooks, you need to Create an Intuit Account. However, if you already have one, click the Sign In button. 
5. Enter your credentials, then click Create Firm. 
6. Once your firm is created, please contact us or click the Help button within your firm's dashboard so our live experts can assist with connecting your companies.

Here's a screenshot for your reference: 

Moreover, once you've set up your accounting firm, here are some helpful articles to guide you in managing pricing plans, projects, and tasks:

• Manage your QuickBooks Online Accountant pricing plan and discount
• Create and manage projects in QuickBooks Online and Accountant
• Manage and track your work with client requests, projects, and tasks in QuickBooks Online Accountant

Feel free to visit this forum if you have any other questions, will97. I'm here to provide prompt responses to your queries.